Low-torque multifilament compact yarn



1968 w. A. TOMPKINS 3,4 5

LOW-TORQUE MULTIFILAMENT COMPACT YARN Filed Sept. 1, 1966 2 sheets-sheet 1 In ventdr [if/44m Hera e Tanmews W/mm Attorneys Oct. 8, 1968 Q w. A. TOMFKINS 3,404,525

LQW'TORQUE MULTIFILAMENT COMPACT YARN Filed Sept. 1, 1966 2 Sheets -Sheet 2 I Inventor Mum/ 4 AW/vue Tamar/us mm if wM A ttorneya United States Patent g 3,404,525 LOW-TORQUE MULTIFILAMENT COMPACT YARN William Arthur Tompkins, Usk, England, assignor to Imperial Chemical Industries Limited, London, Eng-' land Filed Sept. 1, 1966, Ser. No. 576,766 Claims priority, application Great Britain, Sept. 10, 1965,

38,689/ 65 4 Claims. (Cl. 57-440) ABSTRACT OF THE DISCLOSURE A compact multifilament yarn wherein the filaments are parallel and which exhibits a low torque of between .25 and 2.5 turns per inch and has no twist and no crimp. Also, a yarn having the above specified torque and also a twist of .25 turn per inch in the same direction as the torque.

The invention concerns low-torque multifilament compact yarn.

Torque in a yarn results from torsional stress induced by twisting; and it is conveniently expressed as the turns per inch of twist-liveliness measured in the yarn. Owing to the fact that torque decays at a rate dependent on, inter alia, the value of the initial torque and the conditions of yarn storage, the values of torque referred to herein are those present in the yarn when the measurements were made approximately 4 hours after production of the yarn. The values would be significantly different if the measurements were taken after the yarn had been stored for, say, 30 days; for instance a torque of 2.5 turns per inch in 45 denier/l5 filament nylon 66 yarn can decay to one of 2.0 turns per inch over that period.

A compact yarn is one which by virtue of interfilamentary cohesion is manipulable as an entity without defects arising from handling, running, etc.

The traditional manner of compacting a multifilament yarn has been by twisting i.e. by the insertion of unidirectional twist. Twisting, however, imposes limitations on the productivity of yarn production processes, and is not comparable in this respect with pure winding.

Hence, attention has recently been paid to other means of compacting, as for instance alternating twist, filament interlacing and filament adhesion.

The invention concerns a novel multifilament compact yarn, and the method of producing it.

According to the invention, a multifil'ament compact yarn is characterised by the absence of any substantial unidirectional twist and the presence of from 0.25 to 2.5 7

turns per inch unidirectional torque. The narrow range of torque is called for by thene'ed to have sufficient torque to cause the filaments to bind together but not so much a as to lead to handling defects, such as looping or snarling during subsequent pirning, or to fabric defects, such as spiralling of knitted fabric panelsfor stockings, due to excessive twist-liveliness.

By the absence of any substantial unidirection twist, we mean that there shall be twist of, or-less than, the minimum value of K tion, generally 0.25 turn per inch or less.

Experiments have shown that with 60 denier/20 filament and 70 denier/ 34 filament yarn of polyhexamethylene adipamide a truly compact yarn is obtained, which will not giverisetoa tendencyto looping'infl the most significant after-treatment of pirning, without twist and at a torque of 1.5 turns per inch. Such yarns have been used as weft in the manufacture of woven fabrics having no faults attributable to the handling properties of the yarn. With these particular yarns. any increase much producer twist for the yarnin ques 3,404,525 Patented Oct. 8, 1968 ice beyond about 2.0 turns per inch led to an incidence of looping or snarling defects at pirning (say, in 1 out of every 10 pirns); and'a decrease below about 0.5 led to handling difficulties due to filament separation, especially at low speeds (e.g. up to 200 feet/minute). Transfer of the yarns from one package to another at speeds up to 2,400 feet/minute has been achieved satisfactorily at normal yarn transfer tensions when the torque is between 0.5 turn per inch and 25 turns per inch.

Torque of the low degree in question may be introduced in anumber of ways, but the most convenient, from the point of view of productivity, involves the imparting of false twist to the running yarn while it is hot.

Conveniently, such low-torque false twist can be imparted during the drawing process carried outon multifilament yarns of synthetic polymeric material, as for instance polyamide, polyester and polypropylene material. For instance, the false twist can be imparted actually while the yarn is being drawn; or it can be imparted subsequently to the drawing having been effected but prior to wind-up thereafter.

In such drawing process, undrawn yarn is fed into a drawing zone at a predetermined rate, the point of draw normally being localized on a snubbing-pin which is preferably heated, and the yarn is drawn by the action of draw rolls operating at a multiple of the predetermined rate. The yarn is then wound up, either with or Without the imparting of a low degree of twist.

The appropriate low degree of torque can be obtained from a range of combinations of twist insertion and setting, i.e. from low twist with a high degree of set (eg using a heated metal snubbing-pin) to high twist with a low degree of set eg. with a cold metal or ceramic snubbing-pin, or no pin at all and a feed roll).

According to British Patent No. 890,053, false twist may be imparted during the drawing process, by passing the yarn, en route from the snubbing-pir1 to the draw roll, partially around and in frictional contact with a convexsurfaced flange fitted to one end of the draw roll, whereby the yarn is caused to roll about its axis. The flange may be made, for instance, of neoprene of 78 shore hardness; but observing that only a low degree of false twist is needed to be imparted, as opposed to the degree required for crimping as disclosed in the aforesaid specifi cation, other more durable rnaterials such as chromed steel may be used, with a larger angle of wrap of the yarn in contact with the flange than would be required with materials of a higher coefiicient of friction.

It is also possible to impart false twist by means of a twist-tube false twister, either of the sort which acts di- .rectly on the yarn by friction or of the sort which causes and with sensibly zero unidirectional twist. The filaments I are effectively parallel to one another and to the length direction of the yarn.

If desired, in order to reduce the residual shrinkage in the yarn, normally to at least half its normal Value, a heat-relaxing treatment may be carried out on the yarn, concomitantly with false twisting, by passing the yarn over or through a heating device. Such device may, if desired, comprise a jet supplied with heated gas, such as hot air or steam, under pressure, so long as sensibly no filament interlacing or twisting is involved in its use.

Alternatively, the heating device may comprise a cylindrical convection heater supplied with e.g. hot air or steam; or it may comprise a contact heater, preferably a curved plate or plates heated electrically to the desired temperature. It is preferred to utilize the heat imparted for this heat-relaxation treatment for the pre-false-twist- 3 ing' heating also; but if such heat-relaxing is carried-out subsequently to de-twisting, it will be necessary to impart a higher degree of false twist than normal, as the relaxation treatment tends to accelerate the torque decay.

A normal amount of twist is about double that of the torque desired, assuming thorough setting of the twist.

The yarn prior to false twisting is in its normal condition, i.e. it will have the normal amount of spinning finish thereon. It is unnecessary and undesirable to have any solvent applied to the yarn before false-twisting, unless the yarn material is of a kind which will not allow of the setting of twist with heat alone or with heat combined with the action of drawing.

The invention is applicable to all multifilament yarns of any material capable of being set, notably the synthetic yarn materials. Thus, although 60/20 and 70/ 34 yarns have been specifically referred to above, the yarns may be sheerer, as for instance /3 or /7, or they may be heavier,'as for instance 205/34. The polyamides, polyesters and polypropylenes represent the presently most useful yarn materials.

In view of the low torque present in the yarn, it is necessary to withdraw the yarn from its package at a suflicient tension to prevent snarling; but this does not present any difficulty, as the tension will never be likely to be higher than that normally required in any textile process utilizing the yarn as a supply. A low torque may be used to supplement a low twist, so that the combined compacting effect of torque and twist is adequate for the purpose in hand, the values of both being lower than those required when either torque or twist alone is used for compacting of the yarn in question.

The invention will now be described by reference to the accompanying drawings, in which FIGURE 1 is a diagram of drawing apparatus incorporating a rubber flange on one end of the draw roll;

FIGURE 1a is a side elevation-a1 view of the draw roll of FIGURE 1;

FIGURE 2 is a diagram of drawing apparatus with provision for the false-twisting of the drawn yarn and its relaxation in a cylindrical heater;

FIGURE 3 is a diagram of drawing apparatus with provision for the false-twisting of the drawn yarn and its relaxation by contact with a contact heater;

FIGURE 4 is a diagram of drawing apparatus with provision for heating and false-twisting the yarn whilst it is being drawn; and

FIGURE 5 is a diagram of a modified form of the apparatus of FIGURE 1.

tween which sets of rolls the yarn, Y, is drawn, the point of draw being localized by the snubbing-pin 11, which can be either ceramic or metal and around which the yarn is wrapped with two turns. At one end of draw roll 5 is attached curved flange 9,v which may be of rubber or of metal; and the yarn path between snubbing-pin 11 and draw roll 5 makes an angle 0 with the perpendicular to the axis of the draw roll, the value of 0 affecting the amount of torque to be induced by the false twisting action of the flange on the yarn.

In FIGURE 2, a hot air heater 13 with a false twister 19is positioned downstream of draw roll 5; and the drawn yarn is both heat-relaxed and false twisted before being passed via guide 19to a winding mechanism (not shown).

The arrangement of FIGURE 3 is similar to that of FIGURE 2' save that the yarn is relaxed by an amount controlled by the degree of step-down of a stepped draw roll 5, 5a combined with its stepped separator roll 7, 7a. The yarn is fed into the drawing zone by feed roll 1 and nip roll 1a. The heat-relaxing heater in this case is a contact heater 21 of the two-sided (or pyramid) type, the yarn passing in contact with a heated surface of the heater up one side, around pulley wheel 23 and then down the other side of the heater in contact with a heated surfacethereof.

In FIGURE 4, the torque is induced by means of a false twister 17 within the drawing span, the heater (to heat the yarn upstream of the false twister) in this case being a single-sided contact heater 27. The yarn is fed into the drawing Zone 'by feed roll 1 with nip roll 1a, the yarn first being taken on a partial wrap around feed roll 1, thence around grooved ceramic pin 25 and finally between the nip of rolls 1 and 1a.

The arrangement of apparatus shown in FIGURE 5, which is especially for use with heavier denier yarn of Terylene (registered trademark) polyester fibre, is essentially similar to that of FIGURES 1 and 1a, but with the addition of adjustable ceramic pin 29 between an electrically-heated metal snubbing-pin 11, having electric leads 31, and the draw roll 5.

The following examples illustrate but do not limit the invention.

Example I Multifilament yarns of polyhexamethylene adipamide, of the deniers and filament numbers indicated, were drawn, and torque was induced in them, by the apparatus of FIGURES 1 and 1a, the draw roll being provided with a rubber flange of 20 cms. diameter and 5 ems. cross-sectional radius of curvature (see FIGURE 10) and shore hard- In the drawings, the same reference numerals have been ness 87-90 fitted on a draw roll of 10 cms. diameter.

Pin tem- Draw r011 Twist Angle of perature surface Wind up liveliness Yarn used (drawn threadline Snubbing before yarn s eed in speed in in turns denier given) to flange pin was drawn it. minute ttJminute per inch thereon, C.

employed mall the figures where the apparatus concerned 181116 same or directly equivalent. Example II The combined drawing and torque-inducing apparatus of FIGURES 1 and 1a comprises feed roll 1 with its separator roll 3 and draw roll 5 with its separator roll 7, be-

The basic conditions of the example were the same as those of Example I, save that the shore hardness of the rubber flange was 79, its diameter was 9.4 cmsand cross- URE 5. The metal snubbing-pin was heated to 96 C.; sectional radius of curvature1.7,.and the draw rolldiamand the angle between the threadline and the flange was eter was 6 cms. determined by the positioning of the adjustable ceramic Pin tempera- Draw roll Twist Yarn used (drawn denier Angle of ature 0.) surface Wind up liveliness given) Flange surface threadline Snubbing pin beiore yarn speed, speed, in turns to flange was being {t.lmin. fin/min. per inch drawn thereon 15 denier3filaruents Po1ished .{20 W ceramic-.. 1 21 1,850 1,750 1.8 1 do 21 7 1,900 1,750 0.6 Do Matt- 13 rin 21 1, 850 1,800 p 2.0

pin. The flange was 92 shore hardness and 14.5 cms. Example III diameter, fitted to a draw roll of cms.

The basic conditions of this example were the same as I, Angle between threadline Twist liveliness those of Example I, save thatthe flange was of smooth and flange, degree: in t.p.i. chrome-plated metal, its diameter was 14.6 0111s. and cross- 8 0.5 sectional radius of curvature 2.3 cms., and the draw 1.5 roll diameter was 10 cms. 2.0

Pin tempera- Draw r011 Yarn used Angle of Snubbing ture 0.) surface Wind up Twist (drawn denier given) threadline Pin before yarn speed in speedm liveliness to flange was drawn it/min. ft./mm. in t.p.i.

thereon 15 denier 3 filaments 10 metal 125 2,000 1, 900 2 5 4% do 112 2,000 1,900 0 7 11- ceramic..- 21 3,050 3,000 2 1 denier l0 filaments 5 0.- 21 3,050 3,000 1 0 4 21 3, 050 3,000 0 s 17 118 2,000 2, 500 2 5 40 denier 13 filaments .{11- 110 2, 600 2, 500 1 0 o 120 2, 000 2,500 0 s 45 denier 15 filaments gt; Z88 i: 3 2 20. 21 1,100 1,050 0 5 205 denier a4 filaments- Example IV Example VIII In this example, multifilament yarns of polyhexamethyl- 45 denier 15 filament yarn of polyhexamethylene adipene adipamide, of the deniers and filament numbers indiamide was drawn and heat-relaxed whilst torque was cated, were drawn and subsequently heat-relaxed in a induced by the apparatus of FIGURE 4 to which was at- 22-inch long hot air heater whilst torque was induced in ta-ched a ring-spindle wind-up for the insertion of twist. them, by the apparatus of FIGURE 2. The yarn, with residual boiling water shrinkage of from Draw roll Air temper- False twist Wind up Twist Yarn used (drawn speed in ature 0.) head speed speed in l vehness denier given) tt./min. in heater in tt./m1n. 1n t.p.i.

15 denier 3 filaments. 2,000 230 15 1, s50 21 denier 15 filaments 2, 000 215 16 1, 750 1. 8

Example V 4% to 6%, was satisfactory for use in the welts of stock- 45 denier 15 filament yam of polyhexamethylene adip ings when tw1st of 0.25 turn per inch was inserted by the amide was drawn and subsequently heat-relaxed in an Eris: g g i f i to yg i 8% relaxation step whilst torque was induced in it using false twist; t is e g wasdm i y the apparatus of FIGURE The two heating surfaces of nifid antly raised in cd mpa riz ri wh t h e sia m i a id gr oc efis the Pyramid heater were each 6 mchgs long in which it was necessary to impart 0.6-0.7 turn per inch twist.

What I claim is:

Draw roll Contact heater False twist Wind up Twist speed in surface temperhead speed speed in iiveliness -l atllre ga itJminin 1. A compact, synthetic multifilament yarn having no crimp and no substantial unidirectional twist, character.

1.8% gg lg 33? g g ized in that the yarn has a unidirectional torque from 0.25 to 2.5 turns per inch and that the filaments are sub- Example VI stantially parallel to one another and to the length direction of the yarn.

45 denier 15 filament Y 0f Polyhexamethylene P' 2. A compact, synthetic multifilament yarn, characamide was false twist d Whilst being using the terized in that the yarn has a unidirectional twist of not dpp of FIGURE The Contact heater 3 24 greater than 0.25 turn per inch and a torque of from 0.25 inches long; and the yarn was drawn at 800 feet/minute. to 5 turns per inch in the same direction as the said twist. Heater temperature False twist head speed Twist liveliness in Q in mm resultant yamint'ph 3. A compact, synthetic multifilament yarn according to claim 1 and having a residual shrinkage not greater 88g than half its normal value. 1301000 015 4. A compact, synthetic multifilament yarn according Example VII to claim 2, in which the filaments are of poly-hexamethylene adipamide having a residual boiling water shrinkage 150 denier 30 filament yarn of Terylene (registered of between 4% and 6%. trademark) polyester fibre was drawn at 2,130 feet/minute and torque was induced in it by the apparatus of FIG- (References n following page) References Cited UNITED STATES PATENTS Ephland 57157 XR Comer.

Stuewer 57140 XR Biggers 5734 Held 5734 Stoddard et a1. 5734 XR Jenkins et a1. 5734 XR Gonsalves et a1 5734 10 Evans 5734 Olson 5734 XR Deeley et a1. 57157 XR Crouzet 57-157 Chalfant et a1. 5734 Dunwoody 57106 XR FRANK J. COHEN, Primary Examiner.

D. WATKINS, Assistant Examiner. 

